1. Field of the Invention
The present invention relates to novel and useful piperazine derivatives, processes for their production, and pharmaceutical compositions and antiallergic compositions comprising said derivatives as active ingredients.
2. Description of the Prior Art
The inventors of the present invention succeeded in synthesizing propanolamine derivatives of the following formula and found that these compounds are of value as antihypertensive and antiglaucoma agents (JP Application H-6-11844). ##STR2## (wherein R.sub.1 represents hydrogen, lower alkyl or lower alkoxy; R.sub.2 represents isopropylamino, tert-butylamino, 2-(2-methoxyphenyl)ethyl-1-amino, 4-(2-methoxyphenyl)-1-piperazinyl, or 4-piperonyl-1-piperazinyl; provided, however, that where R.sub.1 is hydrogen, R.sub.2 is neither isopropylamino nor tert-butylamino and that where R.sub.1 is methyl, R.sub.2 is not isopropylamino).
The inventors of the present invention thence proceeded with further research into the synthesis and pharmacological profile assessment of related compounds. As a result, they synthesized novel piperazine derivatives and discovered that these compounds are of value as antiallergic agents. Based on those findings, the inventors did further research and have perfected the present invention.